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UCC2818A-Q1: Power Supply Options

SHALINI ADDEPALLI
Prodigy 30 points
Part Number: UCC2818A-Q1
Other Parts Discussed in Thread: UCC28C43-Q1

Hello,

I am building an AC-DC converter with boost PFC which has an output voltage of 390V (1500W) using UCC2818A-Q1 IC.  I am looking into the power supply options for this IC, I do not have any additional power supply, so I am planning to power the IC from the rectified output voltage. Is there any voltage regulator IC which can take a wide output voltage range of 200-400V and give a fixed output voltage? And also is there an application note of how to design the bootstrap power supply for this IC?

Thanks in advance

  • 0
    TI__Mastermind 34465 points

    Hello SHALINI ADDEPALLI,

    Normally you would power this pfc controller from an auxiliary power supply that provides 15V from the rectified mains.
    Since you have chosen an automotive grade pfc controller I suggest you use the UCC28C43-Q1 and you can configure this in a flyback design.

    You will find several reference designs for this part on the web page.

    Regards

    John

  • 0 in reply to John Griffin1
    Prodigy 30 points
    Hello John,

    Thanks for your reply. The UCC28C43-Q1 seems to be for peak current mode control, but I was planning to design the circuit in an average current mode control. Is there any particular reason of why you have suggested this UCC28C43-Q1 IC and a flyback topology. My design output requirements are 1500W, 390V and the input voltage is 240 VAC. So I was planning to design a boost pfc circuit with one of the single phase CCM PFC Controllers (Preferably in average current control mode). So can you please suggest me a PFC Controller IC according to these requirements?

    And also is there any application note on how to design the auxiliary power supply for the UCC2818A-Q1?

    Thanks and Regards,
    Shalini Addepalli
  • 0 in reply to SHALINI ADDEPALLI
    TI__Mastermind 34465 points

    Hello Shalini,

    My commendation is to use the UCC28C43-Q1 as an auxiliary supply to generate the VDD bias power for UCC2818A-Q1 pfc controller.

    You can use one of the many UCC2843 reference designs to generate this bias rail. There is no application note per se that  specifically relates to pfc bias power.

    Regards

    John

  • 0 in reply to John Griffin1
    Prodigy 30 points
    Hello John,

    Now, I understood the solution which you suggested.

    Can we power UCC2818A-Q1 PFC Controller using a bootstrap power supply circuit from the rectifier mains similar to UCC28C43-Q1 (The UCC28C43-Q1 IC runs on a bootstrap power supply circuit as shown in its datasheet). If a bootstrap power supply is used for UCC28C43-Q1 , would it create any problems in the functioning of main boost PFC circuit?

    Thanks and Regards,
    Shalini Addepalli
  • 0 in reply to SHALINI ADDEPALLI
    TI__Mastermind 34465 points
    Hello Shalini,
    The UCC28C43-Q1 can be started up from the high voltage and operated with a bias winding from the flyback transformer. It can do this because this part has been optimised for low bias startup current and a fairly large UVLO(ON) and UVLO(OFF) hysteresis.
    The UCC2818A-Q1 has higher operating currents and its startup current may not even be defined in the data sheet. You should check this.
    Anyway you will find that you need a high wattage startup resistor from the high voltage to the VDD on the UCC2818A-Q1 compared to the UCC28C43-Q1.
    Additionally the flyback will start up fast and reliably. The alternative is to place an auxiliary winding on the main boost inductor .
    This will take longer to start up since the voltage across the main winding is the AC input.
    Regards
    John